While designed partly, mainly, or, it may be, exclusively, to serve military purposes, strategical railways, unlike military railways proper, form part of the ordinary railway system of the country in which they are built. They approximate to commercial lines in construction, equipment and operation, and they are worked in connection with them for the ordinary purposes of trade and travel; though in their case any considerations as to whether the traffic they carry is remunerative does not arise, provided only that they are capable of fulfilling their real purpose—that, namely, of ensuring such military transports as may, sooner or later, be required of them. It is possible that in times of peace the amount of actual traffic passing over them will be comparatively small, if not even practically nil, and that many years may elapse before the special facilities they must necessarily offer,—such as extensive siding accommodation and long platforms for the loading and unloading of troop trains—are likely to be employed to the fullest extent; but they nevertheless form an integral part both of the railway system and of the military system of the country, and, having been constructed, they are, at least, available for military purposes whenever wanted.
One must, however, again bear in mind that a railway built to meet the ordinary requirements of trade and travel does not become a "strategical" any more than a "military" railway simply because, in time of war, it is used, to whatever extent, for the conveyance of troops, supplies or war material. The essential factor in each instance is, not the use that is made of the line, but the particular, or, at least, the main object it has been built to serve. Just, also, as a commercial line remains a commercial line notwithstanding its use for military traffic, so, in turn, a strategical line remains a strategical line whatever the amount of civilian traffic it may carry in time of peace.
Yet while the distinction thus drawn between general railways and strategical railways is abundantly warranted, the increase of the former may still have an important bearing on the operation of the latter because of the improvement of transport facilities in the interior, and because of the greater amount of rolling stock which will be made available for war purposes. "From a military point of view," said von Moltke in the Prussian Herrenhaus on March 26, 1876, "every railway is welcome, and two are still more welcome than one"; and he developed this idea in a further speech on December 17, 1879, when, in declaring that the ownership and operation of the leading Prussian railways was desirable from a military standpoint, he said:—[52]
Railways have become, in our time, one of the most essential instruments for the conduct of war. The transport of large bodies of troops to a given point is an extremely complicated and comprehensive piece of work, to which continuous attention must be paid. Every fresh railway junction makes a difference, while, although we may not want to make use of every railway line that has been constructed, we may still want to make use of the whole of the rolling stock that is available.
Another important distinction between military and strategical railways is that whereas the building of the former will be governed primarily by military requirements, that of the latter may be fundamentally due to considerations of State policy. Strategical railways are wanted to serve the purposes of national defence or, alternatively, of national expansion. They are especially provided to ensure the speedy concentration of troops on the frontier, whether to resist invasion by a neighbouring country or to facilitate the invasion either of that country or, it may be, of territory on the other side thereof. The fact that they have been built may, in some cases, even further the interests of peace, should the increased means they offer for military transports render the country concerned a more formidable antagonist than it might otherwise be, and influence the policy of other States or lands accordingly.
In tropical dependencies the building of railways as a practical proof of "effective occupation" is often regarded as preferable to military conquest, being likely, in most cases, to answer the same purpose while offering many other advantages, besides. In West Africa there are not only railways of this class but others that have, in addition, been designed as a precautionary measure against a not impossible invasion, at some future date, by Mohammedan tribes from North Central Africa. All such lines as these belong to the strategical type, though they may, also, serve an important part in furthering the economic development of the territories concerned.
Strategical railways, whether designed for defensive or aggressive purposes, may, in turn, be divided into two main groups, (1) those that constitute a network of lines; and (2) single or individual lines for short or long distances.
A network of strategical railways is generally found in direct association with frontiers. Single or individual strategical lines fall into various groups including (1) short lines or branches running out to some point on or near to a frontier; (2) single lines carried for long distances, and, possibly, crossing entire continents; (3) circular or short lines, connecting different railway systems with one another, in order to facilitate the movement of troops during mobilisation or concentration or for defensive purposes in the event of invasion; (4) lines passing round cities or large towns in order to avoid delay of troop trains; and (5) lines for coast defence.
The ideal conditions for a network of strategical railways was already a subject of discussion in Germany in 1842, when Pönitz brought forward his proposal that that country should provide herself with such a system. There were, he said, theorists who designed, on paper, strategical railways which, starting from a common centre, radiated in straight lines to different points on the frontier and were connected with one another by parallel or intersecting lines of railway on the principle of a geometrical design, or, he might have added, of a spider's web. Pönitz admitted the excellence of the idea, suggesting that if there were, indeed, a group of lines to the frontier connected by cross lines allowing of a complete interchange of traffic, the enemy would never know at what point a sudden advance in force might not be made, while the linking up of the entire system would greatly facilitate working.